


Perks of the Job

by iinoyb



Category: Undertale (Video Game)
Genre: Ectobiology, M/M, Sanster, Soul Sex, Unresponsible use of the workfloor
Language: English
Status: Completed
Published: 2017-09-01
Updated: 2017-09-01
Packaged: 2018-12-22 16:46:12
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,934
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11971491
Author URL: https://archiveofourown.org/users/iinoyb/pseuds/iinoyb
Summary: Sans and Gaster have some fun on the work floor. (Repost from my old account)





	Perks of the Job

The lab was completely silent, besides the soft scribbling of pen on paper. Sans turned his head slightly to observe his coworker (his boss, actually) diligently writing his notes.

The young skeleton himself had a considerable amount of work lying on top of his desk also, piles of hastily made observations in the middle of time-sensitive experiments, now waiting to be rewritten and compiled into proper scientific studies.

It was the boring part of a job Sans already reluctantly committed to. If it weren't for the aforementioned colleague, he most likely would have quit ages ago.

Oh, and he had bills to pay, of course.

But as he sat there, admiring how his fellow scientist was entirely absorbed in his research, he realized it was mostly the other man that drew him to the tedious work in the labs.

W.D. Gaster was quite the pleasant appearance after all.

Tiny pinpricks of light sat deep in scrunched up eye sockets, darting to and fro in a fast rhythm. His skeleton brow was slightly pulled together in concentration, pale bone unceremoniously interrupted by a jagged crack extending upwards from his right eye. A similar scar ran downwards from the other socket to almost reach his mouth, which was now twitching in a unconscious tic Sans couldn't help but find slightly endearing.

Sans was bored, but he knew just the remedy.

With a casual hand gesture, his pencil made a small arc through the air to hit the focused scientist against the skull, around where his ear would be if he had one.

Gaster startled up, barely avoiding ruining his work with a stray pen swipe, instead having the ink stain his white sleeve. The younger skeleton had to stifle a chuckle at the sight.

An annoyed look was thrown at him, the scientist turning in his chair to regard his subordinate head on.

"Any particular purpose for that, Sans?" He mumbled.

Sans grinned back, trying his best at looking innocent but ending up with an obvious mischievous vibe instead. "Your coat is dirty." He avoided answering the question.

Gaster frowned some more, looking down and noticing that his pale lab coat was indeed blotted with more than just the ink he had just spilled. He often got so absorbed in his work, he forgot to change it between experiments.

For the tiniest of seconds he debated just ignoring his young worker, Sans often got in difficult moods, and continuing his tasks.

But then again, he had been working for a decent while and was in dire need of some distraction. To keep the mind sharp, you know?

Besides, Sans's actions were never what they appeared on the surface, and the young skeleton's body language left little to the imagination.

Oh, so that's what Sans wanted, huh?

In one fluid movement, Gaster got up from his seated position and shrugged the ruined lab coat from his shoulders, carelessly draping it over the chair instead. The gray turtleneck he wore underneath did wonders for his frame, as opposed to the baggy white fabric he had just shredded, and he reveled in the way Sans's body tensed slightly at the sight.

"How careless of me." Gaster sported a slight smirk now as well, slowly approaching his co-workers desk and towering over him from behind, as Sans was still in his seat.

"How are your notes coming along, then?"

He leaned down, placing arms on either side of Sans's considerably smaller frame, effectively inhibiting any further movements.

Had they been the type of monsters that needed air, his breath would be hot against Sans's neck right about now.

"Just fine, doc..." Sans managed to ground out, trying to keep a growing tension out of his voice.  
And failing miserably at it.

He felt large skeleton hands cover his own, phalanges slowly stroking circles into his wrists bones, an almost shy movement which Sans knew could be the precursor of so much more.

"It's going just spiffy..." The young skeleton went on, deepening his voice slightly, the way Gaster liked it.

Seeing the mostly blank pages lying in front of his lab assistant, Gaster couldn't help let out a little huff.

"So it seems..." He bent forward, nuzzling Sans's neck bone softly, than nipping with his teeth, eliciting a small gasp.

The mere sound made Gaster's magic stir within him, allowing a tongue to form to add to his ministrations.  
"Maybe a short break would help you concentrate better."

Sans merely hummed in response, not trusting his voice to stay steady, when a slick appendage lavished his sensitive bones, but instead tilting his skull back to allow for better access.

His wrists were released in favor of hiking up his lab coat and shirt, making them bunch below his armpits, while Gaster ran skilled hands down his spine and across his lower ribs.

"Ah..d-doc..." It was hard to articulate a proper sentence when deft fingers where invading your body in the most delicious ways, but Sans managed anyway, between small pleasured sounds. "Maybe... we should... ugh...move this out of the wa-AAAY~"

Somehow, in between the sensual caresses, Gaster's hand had made it's way up his rib cage and lightly grazed his soul, sending a hot throb of pleasure all the way through his skeleton body.

Magically summoned genitalia were one thing, but nothing quite replaced the hands-on approach.

"Ah... You... you're right." It took Sans entirely to long to realize Gaster was responding to his statement. The older monsters voice sounded strained and moany, his magic now heavily reacting to the obvious waves of arousal coming from the soul beneath him.

That he could get so worked up without being touched himself made Sans grin even wider.

He felt himself being pulled upwards, almost lifted out of his chair, as the offending furniture was hastily cast to the side in favor of Gaster's body, pushing him into the table.

Sans almost chocked when he heard Gaster's lusty voice directly besides his skull. "I'm going to bend you over this desk and fuck you until you can't stand..."

The smaller skeleton moaned softly at the promise, but was confused when nothing more happened, the hands on his body now lingering, almost touching but not quite.

It took him entirely too long to realize the other was waiting for some form of consent, the sentiment making his soul pulse that much harder.

"Ngh... Yes, please." He managed, grinding his pelvis backwards to really bring the point home.

The next moment he was being pushed down, the by now long forgotten papers cushioning his hastily turned face. Sans's hands scrambled for something to hold onto -anything- as his pants were already being roughly pulled down to bunch at his ankles.

He moaned when he felt Gaster's considerable girth against the hole in his pelvis. God, this man didn't waste any time, did he?

The large hands had momentarily repositioned themselves to tightly grip his hipbones, bending and positioning Sans in such a way as satisfied Gaster's particular whims. Then he sunk in.

"A-a-a-h.. ghn..." Sans's face scrunched up in a delicious combination between immense pleasure and pain, teeth gritting at the discomfort of being entered so carelessly.

Gaster left him no time to adjust, pulling out and slamming back in almost immediately, finding a steady rhythm which left Sans moaning and hissing at the dual sensations.

The elder scientist wasn't being particularly gentle... and Sans loved it.

Especially as his magic rushed to accommodate the change in situation, gathering around his pelvis in such a way that made every slide in and out of his body feel slick and hot and just so freakin good...

It felt like every movement was setting his insides on fire in the best way possible, and he could do nothing but lay there and take it.

"mmhn...ah...ffff~" Barely a few minutes had passed, but Sans already felt the slow but steady built of pressure, his magic coursing through his entire body desperately wanting to get out.

Judging by the pleasured sounds Gaster was making above him, the scientist wasn't in a much better state himself.

The smaller skeleton closed his eye sockets, gathering his last vestiges of willpower to concentrate.

He could feel his own soul beating rapidly in his chest, oozing with ecstasy, filled to the brim with magic. Their temporary link made Sans aware of Gaster's soul too, much in the same state as his own, pounding in his rib cage.

With some effort, Sans could... there!

It was like pouring oil on a flame. As their souls tuned into each other the pleasure seemed multiplied tenfold, the already heated arousal that shook their bones growing into a unstable fire.

Sans mewled at the sensation, as he felt Gaster's trusts falter for the barest of moments, before returning in earnest, now truly fucking him into the surface of the desk.

A tongue formed unbidden inside Sans's mouth, his magic now looking for any way to manifest itself that it could find, and it hung out uselessly, drool dripping onto the notes, ruing them thoroughly.

Not that he cared.

One hand left his hip and started snaking its way up his rib cage again, small sparks of pleasure making Sans tremble whenever the fingers brushed his sensitive bones, but not doing anything to elevate the burning desire for release.

"Unggn... P-Please.. Doc... I ne-" The sentence was cut short by the wonderful sensation of Gaster's hand closing firmly around his soul, fingers burying themselves deep into it's slime-like consistency.

Sans wailed, orgasm crashing into him as his magic poured itself out, filling the air and surging through his bones in red-hot pleasure.

He was only dimly aware of a stuttered scream above him before he felt something wet against his ribs, signaling Gaster had reached his peak moments after Sans himself.

The trusts continued for some moments as the elder monster rode out his climax, making Sans moan and shake from the overstimulation, sending shivers off pleasure up his spine. His soul pulsed gently as Gaster removed his fingers, magic feebly trying to stabilize itself, but finding itself completely spent.

Gaster pulled back with a small sound, leaving only the desk as Sans's support, which he clung to gratefully.

He was not going anywhere for the next few hours, thank you very much.

The work notes were reduced to a mess, scattered by erratic movements and stained with brightly colored drool and semen.

Sans pushed himself up slightly, arms trembling from the effort of supporting his own weight.

"Does this mean I'll have to do these all over again?" He managed, usual jovial humor returning to his voice.

Gaster had already tidied himself up, ever the practical monster, and was pulling his lab coat back over his arms.

He looked over at Sans and the mess they had created with a sigh. "Yes."

Sans pouted a bit, sliding himself backwards to land in his chair with a pained hiss as the back of his pelvic bone hit the seat.

Geeze, Gaster hadn't been kidding about that 'not walking anymore' part.

The scientist approached and quickly pressed a skeleton kiss to the younger's skull, making Sans smile.

"But we can take plenty more breaks in between." Gatser muttered against the top of his head, sounding slightly husky as he did so.

Sans's heart gave another pulse at the tone. Talk about an over-active sex drive.

"Sounds good..." He muttered, as the elder returned to his work.

Yes, there were many things about his job Sans despised, but there were some definite perks also.

**Author's Note:**

> Also feel free to visit [my Tumblr](https://iinoyb.tumblr.com/about), I take requests!


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